The present invention relates to method and device for trans myocardial cryo revascularization. More particularly, the present invention relates to a method of conducting trans myocardial revascularization by means of a cryosurgery device. Further, the present invention relates to a cryosurgery device including a plurality of Joule-Thomson heat exchangers which enables to effectively conduct such revascularization procedure.
Trans myocardial revascularization (TMR) procedures including the formation of transmyocardial channels extending from the epicardium to the left ventricular cavity are well known in the art. Such TMR procedures are currently performed by using CO.sub.2 laser or Holmium:YAG laser and are generally known as TMLR procedures.
Various studies have been conducted so as to determine whether such TMLR channels provide significant myocardial perfusion by allowing blood to flow therethrough from the left ventricular chamber into the myocardium.
Histological examinations have revealed that such channels do not provide significant myocardial perfusion. Rather, the channels undergo significant morphologic changes within two weeks, wherein epicardial and endocardial scars appear at the ends of the channels, and wherein the channels are invaded with granulation tissue containing capillaries and lacunar spaces filled with fibrin and red blood cells. After two weeks, the channels are obscured with massive healing response induced by the infraction so that no definitive channels are identified within the healing myocardium.
Thus, it seems that the TMLR (trans myocardial laser revascularization) method fails to provide durable transmyocardial channels and thereby fails to provide significant myocardial perfusion therethrough.
Rather, the healing of the laser induced myocardial burns involves the formation of scar tissue accompanied by neovascularization, which neovascularization may explain the long term therapeutic effect of such TMLR method.
There is thus a widely recognized need for, and it would be highly advantageous to have, cryosurgery method and device for trans myocardial cryo revascularization which enable to form durable transmyocardial channels without causing considerable trauma to the myocardial tissue.
It would be further advantageous to have such method and device which enable to minimize bleeding, and to substantially eliminate the risk of thrombosis, aneurysms or rupture of major blood vessels.
It would be further advantageous to have such method and device which enable to minimize edema and inflammatory response. Further, it would be advantageous to have such method and device which do not completely denature proteins and which enable regeneration of nerve fibers following Wallerian degeneration.
It would be further advantageous to have such method and device which enable to predetermine the location, shape and size of a lesion, thereby minimizing damage to the surrounding area.
Cryosurgery devices including a Joule-Thomson heat exchanger for providing a surface having a fast changing temperature are disclosed in U.S. Pat. Nos. 5,522,870; 5,540,062; and 5,603,221.
However, none of these inventions provides a plurality of cooling and/or heating chambers for effectively pre-cooling and/or pre-heating the incoming gas before it communicates with the operating tip.
Further, none of these inventions provides a plurality of Joule-Thomson heat exchangers for efficiently and rapidly changing the temperature of gas within such chambers so as to efficiently and rapidly change the temperature of the operating tip.
There is thus a widely recognized need for, and it would be highly advantageous to have, a cryosurgery device having a plurality of cooling and/or heating chambers for effectively pre-cooling and/or pre-heating the incoming gas before it communicates with the operating tip.
It would be further advantageous to have such a device which includes a plurality of Joule-Thomson heat exchangers for efficiently and rapidly changing the temperature of gas within such chambers so as to efficiently and rapidly change the temperature of the operating tip.